Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Osaka, Japan.
Department of Anatomy, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Am J Physiol Regul Integr Comp Physiol. 2024 Jun 1;326(6):R461-R471. doi: 10.1152/ajpregu.00038.2024. Epub 2024 Apr 1.
Nutrient absorption is essential for animal survival and development. Our previous study on zebrafish reported that nutrient absorption in lysosome-rich enterocytes (LREs) is promoted by the voltage-sensing phosphatase (VSP), which regulates phosphoinositide (PIP) homeostasis via electrical signaling in biological membranes. However, it remains unknown whether this VSP function is shared by different absorptive tissues in other species. Here, we focused on the function of VSP in a viviparous teleost , whose intraovarian embryos absorb nutrients from the maternal ovarian fluid through a specialized hindgut-derived pseudoplacental structure called trophotaenia. VSP (Xe-VSP) is expressed in trophotaenia epithelium, an absorptive tissue functionally similar to zebrafish LREs. Notably, the apical distribution of Xe-VSP in trophotaenia epithelial cells closely resembles zebrafish VSP (Dr-VSP) distribution in zebrafish LREs, suggesting a shared role for VSP in absorptive tissues between the two species. Electrophysiological analysis using a heterologous expression system revealed that Xe-VSP preserves functional voltage sensors and phosphatase activity with the leftward shifted voltage sensitivity compared with zebrafish VSP (Dr-VSP). We also identified a single amino acid variation in the S4 helix of Xe-VSP as one of the factors contributing to the leftward shifted voltage sensitivity. This study highlights the biological variation and significance of VSP in various animal species, as well as hinting at the potential role of VSP in nutrient absorption in trophotaenia. We investigate the voltage-sensing phosphatase (VSP) in , a viviparous fish whose intraovarian embryos utilize trophotaenia for nutrient absorption. Although VSP (Xe-VSP) shares key features with known VSPs, its distinct voltage sensitivity arises from species-specific amino acid variation. Xe-VSP in trophotaenia epithelium suggests its involvement in nutrient absorption, similar to VSP in zebrafish enterocytes and potentially in species with similar absorptive cells. Our findings highlight the potential role of VSP across species.
营养吸收对动物的生存和发育至关重要。我们之前的关于斑马鱼的研究报告称，富含溶酶体的肠细胞（LREs）中的营养吸收是由电压感应磷酸酶（VSP）促进的，VSP 通过生物膜中的电信号调节磷酸肌醇（PIP）的动态平衡。然而，目前尚不清楚这种 VSP 功能是否在其他物种的不同吸收组织中共享。在这里，我们专注于一种胎生硬骨鱼中的 VSP 功能，其卵巢内的胚胎通过一种称为滋养层的特殊由后肠衍生的假胎盘结构从母体卵巢液中吸收营养。VSP（Xe-VSP）在滋养层上皮中表达，这是一种吸收组织，在功能上类似于斑马鱼的 LREs。值得注意的是，Xe-VSP 在滋养层上皮细胞中的顶端分布与斑马鱼 VSP（Dr-VSP）在斑马鱼 LREs 中的分布非常相似，这表明 VSP 在这两个物种的吸收组织中具有共同的作用。使用异源表达系统进行的电生理分析表明，Xe-VSP 保留了功能性的电压传感器和磷酸酶活性，与斑马鱼 VSP（Dr-VSP）相比，其电压敏感性向左移动。我们还鉴定出 Xe-VSP 的 S4 螺旋中的单个氨基酸变异是导致电压敏感性向左移动的因素之一。这项研究强调了 VSP 在各种动物物种中的生物学变异性和重要性，并暗示了 VSP 在滋养层中的营养吸收中的潜在作用。我们研究了一种胎生鱼类中的电压感应磷酸酶（VSP），其卵巢内的胚胎利用滋养层吸收营养。虽然 VSP（Xe-VSP）与已知的 VSP 具有关键特征，但它独特的电压敏感性源于物种特异性的氨基酸变异。在滋养层上皮中的 Xe-VSP 表明它参与了营养吸收，类似于斑马鱼肠细胞中的 VSP，并且可能在具有类似吸收细胞的物种中也是如此。我们的研究结果强调了 VSP 在不同物种中的潜在作用。
